Plasmas are often used to activate gases placing them in an activated state such that the gases have an enhanced chemical reactivity. In some cases, the gases are activated to produce dissociated gases containing ions, free radicals, atoms and molecules. Dissociated gases are used for numerous industrial and scientific applications including processing solid materials such as semiconductor wafers, powders, and other gases. Properties of activated gases and conditions under which materials are exposed to the gases vary widely depending on the application. Significant amounts of power are sometimes required in the plasma for dissociation to occur.
Plasma sources generate plasmas by, for example, applying an electric potential of sufficient magnitude to a plasma gas (e.g., O2N2, Ar, NF3, H2 and He), or a mixture of gases, to ionize at least a portion of the gas. Plasmas can be generated in various ways, including DC discharge, radio frequency (RF) discharge, and microwave discharge. DC discharge plasmas are achieved by applying a potential between two electrodes in a plasma gas. RF discharge plasmas are achieved either by capacitively or inductively coupling energy from a power supply into a plasma. Microwave discharge plasmas are achieved by directly coupling microwave energy through a microwave-passing window into a discharge chamber containing a plasma gas. Plasmas are typically contained within chambers that are composed of metallic materials such as aluminum or stainless steel or dielectric materials such as quartz, sapphire, yttrium oxide, zirconium oxide, and/or aluminum nitride.
A known problem in the art of plasma generation is that particles are often generated which can, for example, contaminate the plasma generator or chambers coupled to an output of the plasma chamber. A need therefore exists for decreasing the number of contaminant particles in activated gases generated by plasma generation equipment.